/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/ViewModels/NiagaraParameterDefinitionsSubscriberViewModel.h
Get all UNiagaraScriptVariables held by the UNiagaraGraphs of the UNiagaraScriptSourceBases from GetAllSourceScripts().
[TArray](API\Runtime\Core\Containers\TArray)< [UNiagaraScriptVariable](API\Plugins\NiagaraEditor\UNiagaraScriptVariable) * > GetAllScriptVars()